1. Field of the Invention
This invention pertains broadly to the field of plasma generating devices such as those used in the semiconductor processing industry. More particularly, but without limitation thereto, the invention relates to a highly controlled, low temperature, semiconductor processing method/system in which particulate formation is minimized.
2. Description of the Related Art
In the integrated circuit fabrication art, yield losses have been attributed to particulate induced defects. As circuit feature sizes are continually reduced, particularly into the submicron range, particulates have become one of the primary sources of yield losses. To maintain submicron dimensions during device fabrication, low temperature deposition of dielectric films in cold wall reactors has become a common processing step. Yet, a drawback of cold wall depositions is the potential for particle formation.
In the United States Patent referenced above an invention is described that uses a dielectric member for carrying microwave energy into a semiconductor process reaction chamber. By "carrying" microwave energy to a specific preselected location within semiconductor processing equipment, a plasma formed from the energy is more highly controlled, thereby permitting greater uniformity in semiconductor production.
Those in the semiconductor industry know that plasmas are used to facilitate the deposition of selected materials upon semiconductor substrates as well as to etch or remove selected materials from various surfaces.
In the past, plasmas have been formed by coupling radio frequency energy to a gas by way of electrodes, coils or plates or by coupling microwave energy to a gas by way of a hollow waveguide and a resonant cavity. Generally speaking, plasma formation by way of these two techniques has not been as controlled as desired. Though good results have been achieved, those skilled in the art know that if a greater degree of plasma control could be attained, superior semiconductor production will be achieved.
In the referenced patented invention, a high degree of plasma control was made possible by using a dielectric member to carry microwave energy to a specific location within a processing reactor. In one embodiment of the described invention, an inner chamber was placed around the microwave carrying dielectric member and then both of these were inserted into a semiconductor reaction chamber. Though the interior of the reaction chamber was placed under a vacuum, the pressure within the inner chamber surrounding the dielectric member was kept at atmospheric pressure. This prevented plasma from forming directly about the member and caused a plasma to be formed in a controlled manner about the periphery of the inner chamber. To further control plasma formation, the dielectric member could be tapered so that microwave emission occurs at the member's tapered end, and the dielectric member could be tilted within the inner chamber so that plasma formation occurs in an area where the tilted dielectric member and inner chamber are closest.
In order to meet the submicron dimensional requirements of today's integrated circuit technology, an improvement of the described patented invention was derived.